Lepus is a constellation lying just south of the celestial equator. Its name is Latin for hare. Although the hare does not represent any particular figure in Greek mythology, Lepus was one of the 48 constellations listed by the 2nd century astronomer Ptolemy. It is located below the constellation Orion (the hunter), and is sometimes represented as a hare being chased by Orion or, alternatively, by Orion’s hunting dogs.
Lepus Constellation, Hevelius, 1687
Lepus is most often represented as a rabbit being hunted by Orion, whose hunting dogs (Canis Major and Canis Minor) pursue it. The constellation is also associated with some lunar mythology, including the Moon rabbit.
Four stars of this constellation (α, β, γ, δ Lep) forming a quadrilateral are known as ‘Arsh al-Jawzā,’ ‘the Throne of Jawzā’ or ‘Kursiyy al-Jawzā al-Mu'akhkhar,’ ‘the Hindmost Chair of Jawzā’ and ‘al-Nihāl,’ ‘the Camels Quenching Their Thirst’ in Arabic.
[http://www.peoplesguidetothecosmos.com/constellations/lepus.htm]
[http://astropixels.com/constellations/charts/Lep.html]
There are a fair number of bright stars, both single and double, in Lepus:
The white Alpha Leporis (Arneb) is quite similar to Canopus, but much further away.
[https://jumk.de/astronomie/big-stars/arneb.shtml]
Alpha Leporis (α Leporis, abbreviated Alpha Lep, α Lep), also named Arneb, is the brightest star in the constellation of Lepus.
Alpha Leporis has the traditional name Arneb, from the Arabic ‘arnab,’ ‘hare, (‘Lepus’ is Latin for hare). This is a massive star with about 14 times the mass of the Sun. The interferometer-measured angular diameter of this star is 1.77 ± 0.09 mas. At an estimated distance of 2,218 light-years (680 parsecs), this yields a physical size of about 129 times the radius of the Sun. It has a stellar classification of F0 Ib, with the Ib luminosity class indicating that it is a lower luminosity supergiant star. The effective temperature of the outer envelope is about 6,850 K, which gives the star a yellow-white hue that is typical of F-type stars.
Estimated 13 million years old, Alpha Leporis is an older, dying star that may have already passed through a supergiant phase and is now contracting and heating up in the latter phases of stellar evolution, or perhaps is still expanding into the supergiant phase. Based upon its estimated mass, it is expected to end its life in a spectacular stellar explosion known as a supernova.
[https://en.wikipedia.org/wiki/Alpha_Leporis]
Beta Leporis
[http://www.astrosurf.com/agerard/observ/lepus.html]
Beta Leporis, also named Nihal, is the second brightest star in the constellation of Lepus. The traditional name is Arabic for ‘quenching their thirst.’ It is located about 160 light-years (49 parsecs) from the Earth.
It has an apparent visual magnitude of 2.84 and a stellar classification of G5 II. The mass of this star is 3.5 times the mass of the Sun and it is about 240 million years old, which is sufficient time for a star this massive to consume the hydrogen at its core and evolve away from the main sequence, becoming a G-type bright giant.
This is a double star system and may be a binary. The pair was found to be separated by an angle of 2.58 arcseconds at a position angle of 1.4°. Component B has been observed to fluctuate in brightness and is catalogued as suspected variable star NSV 2008.
[https://en.wikipedia.org/wiki/Beta_Leporis]
Hind’s Crimson Star (R Leporis)
R Leporis, sometimes called Hind’s Crimson Star, is a well-known variable star in the constellation Lepus, near its border with Eridanus.
It is a carbon star which appears distinctly red. It is named after British astronomer J. R. Hind, who observed it in 1845. Its apparent magnitude varies from +5.5 to +11.7 with a period of 418–441 days; recent measurements give a period of 427.07 days. There may be a secondary period of 40 years.
R Leporis is too far from earth for its parallax to be measured effectively; Guandalini and Cristallo calculated the luminosity of Mira variables based on their periods. Using a period of 427.07 days, they calculated the bolometric luminosity to be 13,200 L☉. It was estimated to around 1,350 light-years distant, shining with a luminosity approximately 6,689 times that of the Sun and has a surface temperature of 2,980 K.
R Leporis has often been reported as an intense smoky red color, although this is not pronounced when the star is near its maximum brightness. It is reddest when it is dimmest, which occurs every 14.5 months. During these periods it is a candidate for the most-visible reddest star, but this claim is questionable. The red coloration may be caused by carbon in the star's outer atmosphere filtering out the blue part of its visible light spectrum. The star’s discoverer, Hind, reported that it appeared “like a drop of blood on a black field.”
[https://en.wikipedia.org/wiki/R_Leporis]
Zeta Leporis is a star approximately 70.5 light-years (21.6 parsecs) away in the constellation of Lepus. It has an apparent visual magnitude of 3.5, which is bright enough to be seen with the naked eye.
It has a stellar classification of A2 IV-V(n), suggesting that it is in a transitional stage between an A-type main-sequence star and a subgiant. The (n) suffix indicates that the absorption lines in the star’s spectrum appear nebulous because it is spinning rapidly, causing the lines to broaden because of the Doppler effect.
The star has about 1.46 times the mass of the Sun, along with 1.5 times the radius, and 14 times the luminosity. The abundance of elements other than hydrogen and helium, what astronomers term the star’s metallicity, is only 17% of the abundance in the Sun. The star appears to be a very young, probably around 231 million years in age, but the margin of error spans 50–347 million years old.
A size comparison of the asteroid belt of the Solar System (top) and the Zeta Leporis asteroid belt (bottom).
In 1983, based on radiation in the infrared portion of the electromagnetic spectrum, the InfraRed Astronomical Satellite was used to identify dust orbiting this star. This debris disk is constrained to a diameter of 12.2 AU. By 2001 the dust was found to lie within a 5.4 AU radius. The temperature of the dust was estimated as about 340 K. Based on heating from the star, this could place the grains as close as 2.5 AU from Zeta Leporis.
It is now believed that the dust is coming from a massive asteroid belt in orbit around Zeta Leporis, making it the first extra-solar asteroid belt to be discovered. The estimated mass of the belt is about 200 times the total mass in the Solar System’s asteroid belt, or 4×10^23 kg. For comparison, this is more than half the total mass of the Moon. Astronomers found that the dust contained within this belt should have fallen into the star within 20000 years, a time period much shorter than Zeta Leporis’s estimated age, suggesting that some mechanism must be replenishing the belt. The belt’s age is estimated to be 3×10^8 years.
Calculations from 2010 suggest that this star passed as close as 1.28 parsecs (4.17 light-years) from the Sun about 861,000 years ago, or 1.64 parsecs (5.34 light-years) from the Sun about 1 million years ago.
[https://en.wikipedia.org/wiki/Zeta_Leporis]
The red dwarf 2MASS J0523-1403 will still be shining long after most other stars have died.
[https://www.scientificamerican.com/article/a-star-at-the-edge-of-eternity/]
2MASS J0523-1403 is a very-low-mass red dwarf about 40 light years from Earth in the southern constellation of Lepus. With a very faint visual magnitude of 21.05 and a low effective temperature of 2074K it is visible primarily in large telescopes sensitive to infrared light. 2MASS J0523-1403 was first observed as part of the Two Micron All-Sky Survey (2MASS).
The star has a stellar classification of L2.5, and a V-K color index of 9.42. It has a luminosity of 0.000126 L☉, a mass of 0.08M☉, a radius of 0.086 R☉ and an effective temperature of 2074K. These values are currently the lowest known for a main sequence star. Its small radius is at the local minimums of the radius-luminosity and radius-temperature trends. This local minimum is predicted to occur at the hydrogen burning limit due to differences in the radius-mass relationships of stars and brown dwarfs. Unlike stars, brown dwarfs decrease in radius as mass increases due to their cores being supported by degeneracy pressure. As the mass increases an increasing fraction of the brown dwarf is degenerate causing the radius to shrink.
[https://en.wikipedia.org/wiki/2MASS_J0523-1403]
Gliese 229 A and B
Gliese 229 is a red dwarf about 19 light years away in the constellation Lepus. It has 58% of the mass of the Sun, 69% of the Sun’s radius, and a very low projected rotation velocity of 1 km/s at the stellar equator.
The star is known to be a low activity flare star, which means it undergoes random increases in luminosity because of magnetic activity at the surface. The spectrum shows emission lines of calcium in the H and K bands. The emission of X-rays has been detected from the corona of this star. These may be caused by magnetic loops interacting with the gas of the star's outer atmosphere. No large-scale star spot activity has been detected.
A substellar companion was discovered in 1994. Although too small to sustain hydrogen-burning nuclear fusion as in a main sequence star, with a mass of 21 to 52.4 times that of Jupiter (0.02 to 0.05 solar masses), it is still too massive to be a planet. As a brown dwarf, its core temperature is high enough to initiate the fusion of deuterium with a proton to form helium-3, but it is thought that it used up all its deuterium fuel long ago. This object now has a surface temperature of 950 K.
In March 2014, a super-Neptune mass planet candidate was announced in a much closer-in orbit around GJ 229. Given the proximity to the Sun, the orbit of GJ 229b might be fully characterized by the Gaia space-astrometry mission or via direct imaging.
[https://en.wikipedia.org/wiki/Gliese_229]
[https://en.wikipedia.org/wiki/Messier_79]
There is one Messier object in Lepus, M79. It is a globular cluster of magnitude 8.0, 42,000 light-years from Earth. One of the few globular clusters visible in the Northern Hemisphere winter, it is a Shapley class V cluster, which means that it has an intermediate concentration towards its center. It is often described as having a ‘starfish’ shape. M79 was discovered in 1780 by Pierre Méchain.
[https://en.wikipedia.org/wiki/Lepus_(constellation)]
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